The present invention relates to a calendar display wheel guard of a timepiece provided with a calendar display wheel.
The conventional construction of a calendar display wheel guard of a timepiece provided with a calendar is shown in FIGS. 1 and 2.
As shown in FIG. 1, an hour wheel 1 serves as a guide for a calendar display wheel 3. A step portion 1a is provided at an external periphery of the hour wheel 1, and a calendar display wheel guard 2 is fixed via the step portion 1a to thereby guard the calendar display wheel 3. As shown in FIG. 2, a calendar display wheel guide pin 5 is fixed to a back plate 4 as one body and the calendar display wheel 3 is guided by the calendar display wheel guide pin 5 and the calendar display wheel 3 is guarded by fixing the calendar display wheel guard 2.
However, by the method shown in FIG. 1, it is impossible to step with low torque since power from a calendar jumper 12 to position the calendar display wheel 3 is applied to the hour wheel 1 and the friction torque of the rear gear train increases. And as shown in FIG. 2, the construction to prevent an increase in the friction torque of the rear gear train necessitates the calendar display wheel guide pin 5 having a larger diameter than diameter 1b of the hour wheel 1, and a dial 6 provided with a hole 6a larger than an external diameter 5a of the calendar display wheel guide pin 5 becomes necessary and this imposes a large restriction on designing the timepiece. Further, when the dial 6 is positioned underlapping the calendar display wheel guide pin 5, gaps are between the calendar display wheel 3 and the dial 6, and consequently the thickness of the timepiece is hard to be reduce.